Sequence-specific DNA binding proteins, more commonly known as transcription factors, represent a group of molecules within the cell that function to connect extracellular signals to intracellular responses by directly affecting gene transcription. Immediately after an environmental stimulus, these proteins which reside predominantly in the cytosol are translocated to the nucleus where they bind consensus regions in the promoters of various genes and activate or repress the transcription of the respective target gene.
Bc1-6 (also known B-cell CLL/lymphoma 6, zinc finger protein 51 and LAZ3) is a sequence-specific DNA binding transcriptional repressor (consensus DNA-binding site: TTC(C/T)T(A/C)GAA) (Baron et al., Genes, Chromosomes Cancer, 1995, 13, 221-224; Kerckaert et al., Nat. Genet., 1993, 5, 66-70). The gene is expressed in germinal center B- and T-cells and is required for germinal center formation and Th-2 mediated antibody affinity maturation. In addition to cells of B-cell lineage, bc1-6 expression has been demonstrated in muscle tissue and keratinocytes (Kanazawa et al., Pathol. Int., 1997, 47, 600-607). The expression level of bc1-6 is controlled by the antigen receptor via MAP kinase activation which leads to phosphorylation and degradation of bc1-6 by the ubiquitin/proteosome pathway (Niu et al., Genes Dev., 1998, 12, 1953-1961).
Under normal circumstances, bc1-6 mediates transcriptional repression on a wide range of promoters through the process of histone deacetylation and by recruiting (through the BTB/POZ domain) a nuclear hormone receptor co-repressor (SMRT)(Albagli et al., Biochem. Biophys. Res. Commun., 1996, 220, 911-915; Deweindt et al., Cell Growth Differ., 1995, 6, 1495-1503; Dhordain et al., Oncogene, 1995, 11, 2689-2697; Dhordain et al., Proc. Natl. Acad. Sci. U.S.A., 1997, 94, 10762-10767; Dhordain et al., Nucleic Acids Res., 1998, 26, 4645-4651; Seyfert et al., Oncogene, 1996, 12, 2331-2342). It has also been suggested that bc1-6 plays a role in the regulation of apoptosis. Studies in HeLa cells showed that overexpression of bc1-6 induced apoptosis which was preceded by the downregulation of bc1-2 and bc1-X.sub.L, two other apoptosis repressors (Yamochi et al., Oncogene, 1999, 18, 487-494).
Bc1-6 is localized to chromosome 3q27, a region which undergoes a high frequency of translocation events (Ye et al., Cancer Res., 1993, 53, 2732-2735). Deregulation of bc1-6 expression has been shown to occur via translocations with other chromosome sites including those of the 1 g heavy (14q32) or light (2p12) chain loci (Bastard et al., Blood, 1994, 83, 2423-2427; Daudignon et al., Cancer Genet. Cytogenet., 1999, 111, 157-160; Gaidano et al., Blood, 1994, 84, 397-402; Ichinohasama et al., Cancer Genet. Cytogenet., 1998, 104, 19-27; Ohno et al., Jpn. J. Cancer Res., 1994, 85, 592-600; Otsuki et al., Blood, 1995, 85, 2877-2884) as well as through point mutations (Capello et al., Br. J. Haematol., 1997, 99, 168-170; Gaidano et al., Genes, Chromosomes Cancer, 1999, 24, 16-23) and deletions (Bernardin et al., Oncogene, 1997, 14, 849-855; Nakamura et al., Leukemia, 1996, 10, 658-661). These alterations, resulting in aberrant forms of bc1-6, are strongly implicated in the pathogenesis of several types of lymphomas including 30% of diffuse large-cell lymphomas and a fraction of follicular lymphomas (Ye et al., Science, 1993, 262, 747-750). Chromosomal rearrangements involving the bc1-6 locus have also been reported in acute lymphoblastic leukemia (Berger et al., Cancer Genet. Cytogenet., 1996, 86, 76-79) and post-transplant lymphoproliferative disorders (Delecluse et al., Br. J. Haematol., 1995, 91, 101-103).
Currently, there are no known therapeutic agents which effectively inhibit the synthesis of bc1-6 and to date, strategies aimed at investigating bc1-6 function and expression have involved the use of antibodies. Flenghi et al. have used monoclonal antibodies to the altered forms of bc1-6 as diagnostic markers (Flenghi et al., Am. J. Pathol., 1996, 148, 1543-1555; Flenghi et al., Am. J. Pathol., 1995, 147, 405-411). Other methods of detecting the rearrangement of bc1-6 by cleavage and size fractionation are disclosed in U.S. Pat. No. 5,882,858 (Dalla-Favera and Changanti, 1999).
This method is also disclosed in PCT publication WO 94/29343 as well as, in general, nucleic acid molecules that will hybridize to the bc1-6 sequence (Dalla-Favera and Chaganti, 1994).
Consequently, there remains a long felt need for additional agents capable of effectively inhibiting bc1-6 function.
Antisense technology is emerging as an effective means for reducing the expression of specific gene products and may therefore prove to be uniquely useful in a number of therapeutic, diagnostic, and research applications for the modulation of bc1-6 expression.
The present invention provides compositions and methods for modulating bc1-6 expression, including modulation of the aberrant forms of bc1-6.